Audit under income tax act

Yes, it is must...

Note: As per clause 8 of Part-I of First Schedule to the Chartered Accountants Act, 1949, a CA shall be deemed to be guilty of professional misconduct, "if he accepts a position as auditor (statutory, internal, tax auditor, concurrent auditor) which was previously held by another CA or restricted state auditor without first communicating with him in writing".

Hence, communication with previous auditor is must....